Foreword: The science of analyzing how perception works is catching up with L dV
By Richard Alleyne, Science Correspondent
Published: 1:41PM GMT 28 Oct 2009
The secret behind Mona Lisa's enigmatic smile has been explained by scientists who believe it changes depending on which part of the eye sees it first.
One of the charms of the world's most famous painting is that she appears radiant one moment and then serious and sardonic the next.
Now scientists claim to have come up with an answer to her changing moods - our eyes are sending mixed signals to the brain.
They believe Mona Lisa's smile depends on what cells in the retina pick up the image and what channel the image is transmitted through in the brain.
Sometimes one channel wins over the other, and you see the smile, sometimes others take over and you do not see the smile.
Different cells in the eye are designed to pick up different colours, contrasts, backgrounds and foregrounds. Some deal with central vision while others with peripheral.
Depending on what cells picks up the image first depends on what channel they are sent to the brian for interpreting.
These channels encode data about an object's size, clarity, brightness and location in the visual field.
"Sometimes one channel wins over the other, and you see the smile, sometimes others take over and you don't see the smile," said Dr Luis Martinez Otero, a neuroscientist at Institute of Neuroscience in Alicante, Spain, who conducted the study, told New Scientist.
To get a fuller picture of the reasons behind Mona Lisa's vanishing smile, Dr Martinez Otero varied different aspects of the Mona Lisa that are processed by different visual channels, and then asked volunteers whether they saw a smile or not.
The rest is here:http://www.telegraph.co.uk/science/science...atic-smile.html